Variable stroke mechanism



June 18, 1968 Filed Dec. 27, 1966 R. H. HA-AS ET AL 3,388,637

VARIABLE STROKE MECHANI SM 2 Sheets-Sheet 1 J7 AG/TATOR 01. u TCH 0S'C/LL:A TOR Y MO TOR ELECTRIC MOTOR June 18, 1968 R. H. HAAS ET AL VARIABLE STROKE MECHANISM 2 Sheets-Sheet 2 Filed Dec. 27, 1966 Jfin en 0115 Harald f/fflaas W firberi fll'llzzderwood 1 Roam-i United States Patent 3,388,637 VARIABLE STROKE MECHANISM Ronald H. Haas, Lansing, Mich and Herbert N. Underwood, Chicago, Ill., assignors to Borg-Warner Corporation, Chicago, 111., a corporation of Illinois Filed Dec. 27, 1966, Ser. No. 694,938 6 Claims. (Cl. 91-251) This invention relates to oscillatory motors and more particularly to an oscillatory motor having a stroke of variable length.

Most motors which have provision for varying the length of stroke of an oscillating member require the member to be at rest when the adjustment is made. The change of stroke length also normally requires a partial dismantling or disassembly of the motor to accomplish the adjustment.

The present invention overcomes these objections by providing an adjustment which can select any one of at least four stroke lengths by the mere opening or closing of any combination of a pair of valves. The adjustment can be effected with the system in operation or at rest and requires no disassembly of any part of the system.

The desirability of varying the length of stroke of an oscillatory motor becomes obvious when applying this concept to specific systems.

In a washing machine it would be desirable to vary the length of stroke of the agitator depending upon the type of fabric being washed. For coarse or rough fabrics capable of withstanding vigorous agitation a short, choppy stroke would be desirable. For more delicate fabrics, a longer smoother stroke would be preferable.

It would also be advantageous to have intermediate stroke lengths to accommodate a wide range of fabrics.

A further problem frequently encountered in oscillatory motors is the stalling of the motor when it is activated from a stopped position when the valving or oscillating member has come to rest in a position of dead center.

The present invention overcomes this problem by including apparatus so that when the vane or oscillating member of the motor comes to rest the valving of the motor will assume a predetermined position to insure against stalling upon subsequent activation.

It is, therefore, an object of this invention to provide a motor for driving a member through an oscillating stroke, which motor is adapted to allow the length of stroke to be varied by simply opening and closing a pair of valves.

It is a further object of this invention to provide a variable stroke oscillatory motor whose stroke length may be changed while the motor is in operation.

It is a further object of this invention to provide a variable stroke oscillatory motor whose stroke length may be changed without necessitating the disassembly of any part of the system.

It is also an object of this invention to provide a variable stroke oscillatory motor which automatically assumes a predetermined position when coming to rest, such position assuring that upon subsequent activation the motor will begin to operate effectively without danger of stalling.

Referring now to the drawings,

FIGURE 1 is a schematic view of a fluid circuit in which the oscillatory motor of the present invention may be utilized; and

FIGURE 2 is a schematic view of an oscillatory motor embodying the principles of the invention.

There is shown in FIG. 1 a fluid circuit utilizing a variable stroke oscillatory motor constructed in accordance with the principles of the present invention. For purposes of illustration, the variable stroke oscillatory motor is shown in connection with a system for operating an agitator such as the agitator 17 of FIG. 1 which comprises a part of an automatic washing machine (not shown). This arrangement is purely for purposes of illustration of the inherent advantages of the invention and should not be considered as a limitation of the scope of its application. It must be understood that the variable stroke oscillatory motor may be utilized in any system requiring means for providing oscillation of an element of the system and control of the length of the oscillatory stroke.

As best seen in FIGURE 1, a system is shown driving an agitator 17 of a washing machine (not shown). For this purpose a motor 10 is shown connected to drive a pump 11. The pump 11 supplies fluid under pressure for driving the oscillatory motor 15 which drives the agitator 17. The pump 11 has fluid inlet conduit 12 in fluid communication with a sump 13 and a fluid pressure outlet conduit 14 supplying fluid under pressure to an oscillatory fluid motor 15. The oscillatory motor 15 is operably associated with a clutch 16 and in fluid communication with the sump 13 through a conduit 18. The clutch 16 is included for illustration of a system and is not essential to this embodiment. The oscillatory motor 15 is oscillated by the fluid pressure delivered from the pump 11 and transmits this oscillating motion through clutch 16 to the agitator 17.

Referring now to FIGURE 2, the oscillatory motor 15 includes a housing 19 having a pair of spaced apart valve mechanisms of similar structure generally indicated as 20 and 21 and a chamber 22. Only valve mechanism 2% is described. Corresponding parts of valve mechanism 21 have the same number with the sufiix A added.

The housing 19 defines a first bore 23 and a second bore 24 concentric with the first bore and of smaller diameter. The bore 23 includes a bore segment 25 and a bore segment 26 which are axially spaced and are formed over the same diameter.

Intermediate the bore segments and in fluid communication with the bore 23 are a fluid pressure chamber 27 which receives fluid through a port 28 from the fluid pressure outlet conduit 14 (shown in FIGURE 1) and a fluid return chamber 29 which receives fluid from the chamber 22 and communicates it to the sump 13 through conduit 18. These chambers are in communication with a fluid delivery line 32 which in the pressure portion of the cycle receives fluid under pressure from the fluid pressure chamber 27 through a segment 33 of the bore 23 and in the exhaust portion of the cycle delivers fluid to the fluid return chamber 29 through segment 34 of the bore 23. A pin stop 30 is fixed in the housing 19, between bore segments 33 and 34 perpendicular to the axis of bore 23 to limit the downward travel of valve mechanism 20.

A variable stroke pressure chamber 35 is shown in fluid communication with fluid pressure chamber 27 intermediate the bore segments 25 and 26. A bore segment 35 extends from the bore segment 26 to the chamber 22 and is smaller in diameter than the bore segments 25 and 26. A cylindrical recess 37 is provided at the end of bore segment 36 for the purpose of housing a seal 38.

A first fluid passage 41 is provided for conducting fluid under pressure from the fluid pressure chamber 27 to the variable stroke pressure chamber 35. A 3-way valve 42 is provided in passage 41 intermediate the fluid pressure chamber 27 and the variable stroke pressure chamber 35, and controls the flow of fluid either from the fluid pressure chamber 27 to the variable stroke pressure chamber 35 or from the variable stroke pressure chamber 35 to Sump.

A second fluid passage 43 conducts fluid under pressure from the fluid delivery line 32 to the second bore 24A for the purpose of which will soon become apparent.

A third fluid passage 44 conducts any fluid which may have entered the bore segment 26 to sump 13.

Within chamber 22 is mounted a rotary actuator 45 having an integral hub section 46 and a vane 47. The hub section 46 is journalled for rotation about a vertical axis extending along the center of a shaft 48 which is connected to the agitator 17. The chamber 22; is alternately fed by fluid delivery lines 32 and 32A which deliver fluid under pressure to act against the vane 47 rotating the rotary actuator 45 first in one direction then another imparting an oscillating motion to the agitator 17.

A cylindrical spool valve 50 moves within and along the axis of the bore 23 and has a pilot section 51 moving within the second bore 24 and two lands 52 and 53 spaced apart by valve section 54 which has a substantially smaller diameter than the lands 52 and 53. The land 53 separates the valve section 54 and a valve section 55 which is substantially smaller in diameter than the land 53. A pin 56 is provided in valve section 55 extending radially outward from it and perpendicular to the bore axis.

The valve 56 alternately assumes one of two positions, the upper position (illustrated by valve Sii in FIG. 2) and the lower position (illustrated by valve 50A in FIG. 2).

In the upper position, the land 52 along substantially its entire length, is in contact with the bore segment 25 and the smaller diameter valve section 54 allows the fluid pressure to flow from the fluid pressure chamber 27 through the bore segment 33 through the fluid delivery line 32, and into the chamber 22 where it acts against the vane 47 of the rotary actuator 45. The land 53 is positioned so as to restrict the flow of fluid into the fluid return chamber 29.

In the lower position the land 52 is partially in contact with the bore segment 25 at its upper end, the lower shoulder resting against pin stop 30 positioned so as to restrict the flow of fluid from the fluid pressure chamber 27 to the bore 23. The land 53 is positioned substantially within the variable stroke pressure chamber 35 and the smaller diameter valve section 54 allows fluid to flow from the chamber 22 through the fluid delivery line 32 and the bore segment 34 to the fluid return chamber 29.

A valve extension 57 in contact with the valve 50 when acted upon by the vane 47 will cause the valve 50 to move from the lower position to the upper position.

The valve extension 57 is composed of a cylindrical, hollow land section 58, whose wall 59 is interrupted by a pair of grooves 60 spaced 180 degrees apart, and a cylindrical protuberance 62 having a smaller diameter than the land section 58.

The grooves 60 serve as guides within which slide the pin 56. The groove ends limit the travel of the pin 56 and hence limit the distance between the land 53 and the land section 58.

The land section 58 slides in contact with the bore segment 26 and the protuberance 62 slides in contact with the bore segment 36 and extends into the chamber 22.

A spring 63 is positioned in the bore 23 in contact with the land 52 of the valve 50 which serves to urge the valve 50 to come to rest in the lower position when the oscillatory motor 15 is not in operation.

A spring 64 is positioned in the bore 23A in contact with the valve extension 57A which spring 64 serves to urge the valve 56A to come to rest in the upper position when the oscillatory motor 15 is not in operation.

The net result of the springs is that when the agitator circuit is deactivated the valves 50 and 50A assume a predetermined position, thereby eliminating the possibility of both valves 50 and 50A coming to rest in a position blocking pressure flow or both valves blocking flow to sump which would stall the rotary actuator 45 in a subsequent activation of the agitator circuit, thereby preventing operation of the oscillatory motor 15.

In operation when the electric motor is activated it drives the pump 11 so as to draw fluid from the sump 13 through the fluid inlet conduit 12 and discharge the fluid under pressure through the fluid pressure outlet conduit 14 which communicates the fluid pressure to the oscilla- 4 tory motor 15.-The oscillatory motor 15 drives the agitator 17 through the clutch 16.

Assuming the valves 50 and 50A to be in their predetermined equilibrium positions (valve Sit in lower position and valve 50A in upper position) and assuming both 3-way valves 42 and 42A are oriented so as to communicate no fluid pressure to either of the variable stroke pressure chambers or 35A, when the fluid pressure chamber 27 receives fluid pressure from pump 11 through fluid pressure outlet conduit 14 and through port 28 the fluid pressure enters the bore segment 33A and flows directly into the fluid delivery line 32A. The fluid pressure enters the chamber 22 and acts against the vane 47 of the rotary actuator causing the rotary actuator to rotate about its axis in a clockwise direction and drive the agitator 17 by means of the shaft 48 connecting the rotary actuator 45 and the agitator 17. Fluid pressure is simultaneously communicated through the second fluid passage 43A from the fluid pressure deliverly line 32A to the second bore 24 above the pilot section 51. This pressure is applied against the end surface of the pilot section 51 to urge valve 50 to move down-ward until the land 52A strikes pin stop 30A sealing ofl the flow of pressure to the fluid delivery line 32 and putting the fluid delivery line .32 in fluid communication with the fluid return chamber 29.

The rotary actuator 45, after being set in motion continues to rotate in the clockwise direction until the vane 47 strikes the protuberance 62 and causes the valve 50 to move from the lower position to the upper position. The fluid pressure chamber 27 is now in fluid communication with the fluid delivery line 32 which communicates pressure to the chamber 22 and, through the second fluid passage 43, to the second bore 24A above the pilot section 51A. This fluid pressure acts against the upper surface of the pilot section 51A forcing valve 50A to move downward until the land 52A strikes pin stop 30A blocking the flow of fluid from the pressure chamber 27 to the fluid delivery line 32A and placing fluid delivery line 32A in communication with the fluid return chamber 29.

The fluid pressure now is communicated through the fluid delivery line 32 to the chamber 22 and acts against the vane 47 forcing it to rotate in a counterclockwise direction and this motion as before described being transmitted to the agitator.

The fluid previously introduced into the chamber 22 from the fluid delivery line 32A is now forced by the vane 47 to flow back through the fluid delivery line 32A through bore segment 34A and into the fluid return chamber 29.

The rotary actuator 45 continues to rotate in the counterclockwise direction until the vane 47 strikes the protuberance 62A and moves valve 50A from the lower position to the upper position and the cycle begins over.

The length of the arc which the vane 47 describes and therefore the length of the agitator stroke depends on the length and position of the protuberances 62 and 62A. The greater the are through which the vane 47 may rotate before striking a protuberance 62, the longer the agitator stroke will be; the longer the protuberance 62, the shorter the stroke of the agitator.

When the 3-way valve 42 is oriented in the proper direction, fluid pressure flows from the fluid pressure chamber 27 through the first fluid passage 41 through the 3-way valve 42 into the variable stroke pressure chamber 35. This fluid pressure acts against the upper and inner part of the land section 58 of the valve extension 57 forcing the valve extension 57 to slide axially apart from the land 53 until the pin 56 strikes the end of the groove at which point the valve extension 57 and the land 53 are at a predetermined distance. This distance is maintained by the pressure acting against the land section 58, which pressure is sufficient to exert a greater force to separate the land 53 and the valve extension 57 than the force exerted on the valve extension 57 by the vane 47. This insures that the distance will remain the same between the land 53 and the valve extension 57 both before and after the valve extension 57 is struck by the vane 47.

When the 3-way valve 42 is positioned to block the fluid flow to the variable stroke pressure chamber 35 the fluid in the variable stroke pressure chamber 35 is communicated to the sump 13. The vane 47 strikes the protuberance 62 and exents a force which tends to squeeze together the valve extension 57 and the land 53, forcing fluid from the variable stroke pressure chamber 35 through the 3-Way valve 42 to the sump 13.

If the predetermined separation between the land 53 and the valve extension 57 is different for valve 50 than for valve 50A, we have a system allowing four different stroke lengths by pressurizing neither or both or one or the other of the 3-way valves 42 and 42A.

The longest stroke would obviously be attained when both of the valves were closed and no pressure was admitted to the variable stroke pressure chambers 35 and 35A.

The shortest stroke would result when both valves were open. Opening only the valve pressurizing the chamber having the larger separation between the land 53 and the valve extension 57 would give a stroke shonter than the longest stroke and longer than the shortest stroke. Opening only the valve pressurizing the chamber having the shorter separation between the land 53 and the valve extension 57 would give a stroke longer than the previous stroke, but still shorter than the longest stroke.

If the larger separation occurs between the land 53A and the valve extension 57A and if the geometry is determined correctly, the following might be an example of the varying stroke lengths:

Valves open: Stroke length, degrees Neither 180 42 (only) 160 42A (only) 100 42 and 42A 80 The above variations in stroke length may be modified and tailored to individual needs. The desired stroke lengths may be predetermined and the length of the protuberances 62 and the grooves 60 designed accordingly to give the desired results.

Various of the features of this invention have been particularly shown and described; however, it should be obvious to one skilled in the art that various modifications may be made therein without departing from the scope of the invention.

What is claimed is:

1. A variable stroke oscillator motor for oscillating an element of a system and controlling the length of the oscillatory stroke comprising:

(A) a housing defining a chamber;

(B) an output shaft extending through said chamber;

(C) a rotary actuator journaled for rotation within said chamber and connected to said output shaft, said rotary actuator including a vane dividing said chamber into high and low pressure portions;

(D) valve means for alternately communicating fluid pressure to each side of said vane including;

(1) a pair of slidable spool valves mounted within said housing,

(2) a pair of valve extensions in contact with said spool valves, said extensions protruding into said chamber and adapted to actuate said spool valves when contacted by said vane, at least one of said valve extensions adapted to move relative to said spool valve upon the application of pressure to said valve extension,

(E) means to selectively communicate fluid pressure to said extension to change the effective length of the combination of said extension and said spool valve whereby the stroke of said actuator may be varied.

2. A variable stroke oscillatory motor as in claim 1 in which said valve extension is adapted to move axially away from said valve upon the application of pressure to said valve extension.

3. A variable stroke oscilatory motor as in claim 1 wherein said means to selectively communicate fluid pressure to said extension includes at least one 3-way valve operable to communicate fluid pressure to said valve extension or to communicate fluid pressure from said valve extension to sump.

4. A variable stroke oscillatory motor as in claim '1 including biasing means which urge at least one of said slidable spool valves to assume predetermined position when the motor is deactivated to prevent stalling upon subsequent activation.

5. A variable stroke oscillatory motor as in claim 1 wherein said pair of valve extensions in contact with said spool valves protrude into said chamber and each of which extensions are adapted to be struck by said vane and to act to reverse the direction of rotation of said vane by changing the position of the spool valve in contact with the valve extension which is struck so as to communicate fluid pressure to said vane in a direction so as to reverse its direction of rotation.

6. A variable stroke oscillatory motor, including:

(A) a housing defining a chamber;

(B) an output shaft extending through said chamber;

(C) a rotary actuator journalled for rotation within said chamber and connected to said output shaft, said rotary actuator including a vane dividing said chamber into high and low pressure portions;

(D) valve means for alternately communicating fluid pressure to each side of said vane, including;

(1) a pair of spaced apart, parallel cylindrical bores,

(2) a pair of spool valves adapted to slide within said bores,

(3) a pair of valve extensions in contact with said spool valves which extensions protrude into said chamber and each of which are adapted to be struck by said vane and act to reverse the direction of rotation of said vane by causing a change of position of both spool valves to communicate fluid pressure to the low pressure side of the chamber and to communicate fluid pressure from the high pressure portion of the chamber to sump, each of said extensions being further adapted to slide along the axis of and away from said spool valves upon the application of fluid pressure to said valve extensions and further adapted to maintain this separation from said spool valve when acted upon by said vane,

(E) means to selectively communicate fluid pressure to said extensions, including two 3-way valves and two variable stroke pressure chambers, said 3-way valves being operable to communicate pressure either to said variable stroke pressure chambers to act against said valve extension or from said variable stroke pressure chamber to said sump to relieve pressure exerted against said valve extension;

(F) biasing means to urge said slidable spool valves to assume a predetermined position when the motor is de-activated, assuring communication of fluid pressure to a predetermined side of the chamber and communication of the other side of the chamber to sump to prevent stalling upon subsequent activation.

References Cited UNITED STATES PATENTS 700,064 5/1902 Markham 91279 1,019,388 3/1912 Weber et a1. 9l339 1,313,867 8/1919 Mercer 9133l 1,674,056 6/1928 Oishei ct al 9l323 MARTIN P. SCHWADRON, Primary Examiner.

PAUL E. MASLOUSKY, Examiner. 

1. A VARIABLE STROKE OSCILLATOR MOTOR FOR OSCILLATING AN ELEMENT OF A SYSTEM AND CONTROLLING THE LENGTH OF THE OSCILLATORY STROKE COMPRISING: (A) A HOUSING DEFINING A CHAMBER; (B) AN OUTPUT SHAFT EXTENDING THROUGH SAID CHAMBER; (C) A ROTARY ACTUATOR JOURNALED FOR ROTATION WITHIN SAID CHAMBER AND CONNECTED TO SAID OUTPUT SHAFT, SAID ROTARY ACTUATOR INCLUDING A VANE DIVIDING SAID CHAMBER INTO HIGH AND LOW PRESSURE PORTIONS; (D) VALVE MEANS FOR ALTERNATELY COMMUNICATING FLUID PRESSURE TO EACH SIDE OF SAID VANE INCLUDING; (1) A PAIR OF SLIDABLE SPOOL VALVES MOUNTED WITHIN SAID HOUSING, (2) A PAIR OF VALVE EXTENSIONS IN CONTACT WITH SAID SPOOL VALVES, SAID EXTENSIONS PROTRUDING INTO SAID CHAMBER AND ADAPTED TO ACTUATE SAID SPEED VALVES WHEN CONTACTED BY SAID VANE, AT LEAST ONE OF SAID VALVE EXTENSIONS ADAPTED TO MOVE RELATIVE TO SAID SPOOL VALVE UPON THE APPLICATION OF PRESSURE TO SAID VALVE EXTENSION, (E) MEANS TO SELECTIVELY COMMUNICATE FLUID PRESSURE TO SAID EXTENSION TO CHANGE THE EFFECTIVE LENGTH OF THE COMBINATION OF SAID EXTENSION AND SAID SPOOL VALVE WHEREBY THE STROKE OF SAID ACTUATOR MAY BE VARIED. 